K-State Electronic Theses, Dissertations, and Reports: 2004 -
Permanent URI for this collectionhttps://hdl.handle.net/2097/4
This is the collection for doctoral dissertations and masters theses and reports submitted electronically by K-State students. Electronic submission of doctoral dissertations was required beginning Fall semester 2006. Electronic submission for masters theses and reports was required beginning Fall 2007. The collection also contains some dissertations, theses, and reports from the years 2004 and 2005 that were submitted during a pilot test project. Some items before 2004 have been digitized and are available in K-State Electronic Theses, Dissertations, and Reports: pre-2004. Check the Library catalog for dissertations, theses, and reports not found in these collections.
All items included in this collection have been approved by the K-State Graduate School. More information can be found on the ETDR Information Page. Items within this collection are protected by U.S. Copyright. Copyright on each item is held by the individual author.
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Item Open Access Diagnostic approaches to transboundary and zoonotic diseases(2025) Bold, DashzevegTransboundary animal diseases (TADs), including those caused by African swine fever virus (ASFV), Classical swine fever virus (CSFV), and Foot-and-mouth disease virus (FMDV), as well as highly contagious zoonotic agents such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), pose significant threats to agriculture and public health globally. Early detection and follow-up measures are critical for the management of these infectious diseases. In the laboratory, polymerase chain reaction (PCR) is the most commonly used method for diagnosing these pathogens; however, in order to rapidly identify and prevent the spread of these highly infectious viruses, point-of-care (POC) diagnostic assays for the detection of the pathogen’s genetic materials, antigens (Ag), and antibodies (Ab) in the field are necessary. In this dissertation, lateral flow assays (LFAs) for ASFV Ag and Ab detection, multi-antigen print immunoassays (MAPIAs) for ASFV and FMDV Ab detection, and indirect ELISAs for SARS-CoV-2 Ab detection were established. It was also demonstrated that POC approaches used in a low-income country were able to identify ASFV, CSFV, and FMDV genetic sequences in suspect materials, proving the feasibility of POC diagnostics for these pathogens in low resource environments. As a result of this thesis, valuable tools were generated for improving the detection and diagnosis of ASFV, CSFV, FMDV, and SARS-CoV-2.Item Embargo Evaluating the Efficacy of Nutrient Solution Reuse in Hydroponics(2025) Tetteh, MillicentNutrient solution reuse in hydroponics is a sustainable strategy to improve resource efficiency. However, increased microbial risks, nutrient toxicity, and accumulation of allelochemicals can compromise system safety and crop yield. The first objective of this study they are not specifically tailored to hydroponic nutrient solutions. This review synthesizes current knowledge on the risks and opportunities of nutrient reuse in hydroponic systems, highlighting emerging treatment technologies and the urgent need for hydroponics-specific, science-based standards to ensure both sustainability and food safety to support production by small scale farmers. In the second objective, we evaluated the combined performance of slow sand filtration (SSF), biochar filtration, and UV-C disinfection for multi-cycle reuse of hydroponic nutrient solution in romaine lettuce production and assessed the impact of treated nutrient solutions use of plant growth and nutritional quality. Results showed that SU (SSF + UV-C) and SBU (SSF + Biochar + UV-C) consistently achieved ≥5 log₁₀ reductions of E. coli, meeting World Health Organization (WHO) microbial safety criteria. Physically, turbidity remained <2 NTU, and SBU showed the highest light transmittance. Chemically, both treatments reduced ammonium-N, total N, and total P, with SBU showing the highest removals. However, nitrate levels remained relatively stable, calcium steadily accumulated across cycles, and pH in SU and C fell below Food and Agriculture Organization (FAO)/World Health Organization (WHO) guidelines. Micronutrient analysis revealed substantial declines in Fe, Zn, Cu, and Mn—up to 90–97% in SBU resulting in progressive micronutrient imbalance despite EC-based nutrient supplementation. Romaine lettuce grown in SU initially produced the highest biomass but declined by ~30% across cycles, while SBU showed even larger reductions (~45%). Chlorophyll, SPAD, and vitamin C decreased in all treatments, reflecting micronutrient depletion, salinity stress, and oxidative damage. The freshwater treatment also experienced reduced quality due to ammonium accumulation. Overall, combining SSF, biochar, and UV-C provides effective microbial inactivation and maintains physical water quality but progressively depletes essential micronutrients, limiting long-term crop performance. These findings highlight the potential of low-cost treatment systems for small-scale hydroponic growers while emphasizing the need for cycle-specific micronutrient supplementation to sustain yield and nutritional quality during extended nutrient-solution reuse.Item Open Access Fed Cattle Basis Risk under Grid Pricing(2025) Alderson, CaitlynHedging risk in fed cattle markets has become increasingly important as producers face elevated price volatility and market uncertainty. This challenge is particularly pronounced for producers marketing cattle using grid pricing systems, which reward or penalize producers based on carcass attributes such as yield grade, quality grade, and carcass weight. Grid pricing has expanded rapidly over the last decade to represent about 70% of fed cattle marketings. Despite its prominence, little is known about how basis risk changes when cattle are priced using grids instead of traditional live or dressed pricing. With more variable factors impacting realized net price, we expect basis risk increases when cattle are sold on a grid. While grid pricing offers opportunities to capture premiums for higher-quality cattle, it also exposes producers to downside risk due to discounts applied to cattle that do not meet desired specifications. Managing this dual exposure to both price and quality-related premium/discount risks requires quantifying the price risk managed through traditional live or dressed price hedging. It also involves understanding the risk that remains due to varying cattle quality and associated grid component value variation. Results will inform producers using grid pricing of unhedgeable risk using traditional price risk management tools of futures and Livestock Risk Protection. Depending on the magnitude of elevated price risk, additional price risk management instruments might be warranted to manage price risk more effectively. For example, developing a Choice-Select spread or other price risk management market may be valuable. The objectives of this thesis are to quantify how fed cattle hedging risk has changed and to identify the main determinants of hedging risk for grid-priced fed cattle. A key measure is basis risk, the difference between the realized and predicted basis under various fed cattle valuation systems, and the uncertainty of cattle quality. Unique to this study is the adjustment of the predicted basis based on how cattle are priced and the expected quality distributions of cattle of varying quality and premiums/discounts, providing an essential contribution to better understanding contemporary fed cattle basis risk. Hedging risk changes as uncertainty on cattle quality and premiums and discounts are introduced: 1. We start by quantifying traditional weekly basis risk for cash-negotiated cattle over 20 years (2005-2024). This provides a baseline to illustrate historical trends and the evolution of basis risk. 2. Next, risk is quantified on a weekly basis for constant cattle quality (used broadly here to include quality grades, yield grades, carcass weights, etc.), letting premiums and discounts vary over time. Constant carcass quality distributions are averages based on more than 10,000 pens of packing plant grid carcass data obtained from commercial feedyards. This step enables us to determine how introducing varying premiums and discounts affects traditional hedging risk. 3. The analysis then incorporates quality and premium variability over time assuming producers have perfect foresight of quality of each pen hedged. To accomplish this analysis, a random pen of cattle is selected each week from the commercial feedyard data noted above. In this way, quality variation is introduced, but since it is assumed that the producer perfectly anticipates the quality of each pen, there is no quality uncertainty. This segment enables incremental measurement relative to the previous scenario of how introducing quality variation impacts hedging risk and premium/discount variation over time. 4. Finally, imperfect quality guesses are introduced by adding random errors to predicted quality distributions based on the above-referenced feedyard data. This segment enables incremental variation from above scenarios adding quality uncertainty. My approach highlights increasing complexity and variability in basis risk as grid pricing systems dominate the market. Understanding this complexity is critical for producers because it directly impacts the effectiveness of traditional risk management tools. Producers, policymakers, and market participants must recognize these dynamics to develop innovative tools and strategies that better address the unique risks posed by grid pricing. Price risk management in fed cattle markets is of greater importance than ever, with high price levels and elevated price risk. However, traditional hedging instruments are designed for hedging commodity cattle sold using negotiated cash prices. However, with grid pricing, valuing cattle based on carcass merit has become the dominant fed cattle valuation method, and the basis risk for cattle hedging is poorly understood. Traditional hedging instruments enable only base price protection but do nothing to manage varying premiums and discounts on uncertain cattle carcass quality. This study will demonstrate how basis risk changes as cattle are grid-priced and quantify the amount of price risk unhedged for grid-valued cattle. The study will also explain how much of this variation is due to premium/discount variation and uncertainty about varying cattle quality. The findings will provide critical insights for evolving price risk management tools for cattle producers and inform policymakers in designing LRP risk management programs. Depending on the extent of unhedgeable risk identified, new price risk management tools or institutions may be needed to mitigate the increasing price risk associated with grid pricing.Item Embargo Modifying Functional and Nutritional Properties of Pulse Flours and Starches by Roller Milling and Thermal Processes(2025) Qi, JingFunctional and nutritional properties of pulse flours and starches were enhanced by controlled roller milling and thermal processes, with an emphasis on increasing resistant starch (RS) content and understanding factors that influence starch digestibility. In Chapter 1, a comprehensive review highlighted the nutritional significance of pulses, particularly dry peas, lentils, and chickpeas, which are rich in dietary fiber, slowly digestible starch (SDS), and RS. This chapter discussed how pulse-based ingredients, especially flours, can be strategically used in food applications to reduce glycemic response and enhance satiety. In Chapter 2, the molecular structure of pea starch was analyzed, and its amylose content was measured by four methods and compared with starches from maize, potato, and high amylose maize. Pea starch had ~38–40% amylose content as measured by iodine colorimetric, differential scanning calorimetry (DSC), and gel-permeation method (GPC) methods. The Concanavalin A method yielded a lower value (30.4%), suggesting the presence of clustered short branches in pea amylose. The findings highlight the importance of method selection in characterizing starch structure. Given their high amylose content, pea and high amylose maize starches were selected for the production of starch spherulites. In Chapter 3, DSC and a Parr reactor were used to investigate spherulite formation. Spherical crystalline aggregates, known as starch spherulites, were successfully formed from both starches through a controlled thermal process involving heating followed by controlled cooling. Under optimized conditions, both pea and high amylose maize starches formed B-type crystalline spherulites, highlighting the potential for scalable production and future applications in targeted nutrient delivery. In Chapter 4, dry roller milling was used to generate pulse flours from yellow peas, chickpeas, and lentils with varying cell wall integrity. Coarse-sized flours retained more intact cotyledon cell walls, leading to significantly reduced starch digestibility and higher RS levels, particularly after cooking. Chapter 5 focused on the thermal properties of dehulled pulse flours at different moisture levels using DSC. Distinct thermal behavior was observed among the flours and their components (isolated starch, protein fractions), providing fundamental knowledge for the hydration-dependent functional performance of pulse ingredients. In Chapter 6, a novel heat moisture treatment (HMT) protocol was developed and applied to pulse flours to enhance their structural and nutritional qualities. HMT led to increased RS and total dietary fiber content, altered thermal transitions, and reinforced starch crystallinity, demonstrating its potential to improve starch-protein interactions and enzymatic resistance. Chapter 7 summarized the overall conclusions and future research directions. Overall, this dissertation integrates molecular analysis, starch crystallization, flour processing, and thermal/digestibility profiling across seven chapters, advancing the understanding of how pulse starch and flour properties can be optimized for nutritional and functional applications.Item Open Access Community economic development in two rural Kansas communities: a thematic analysis(2025) Colle, KevinRural communities across Kansas face growing challenges of population decline, limited financial resources, and shifting economic structures. This study examines the factors that shape community economic development (CED) in two rural Kansas towns, Sterling and Nickerson, using the Community Capitals Framework (CCF) as an analytical lens. The CCF identifies seven interrelated forms of capital that collectively influence a community’s development trajectory. Through a qualitative comparative case study approach, nine semi-structured interviews were conducted with local leaders and stakeholders from both communities. Data were coded deductively using the seven capitals and analyzed inductively through thematic analysis. Findings reveal four interrelated themes shaping CED in these communities: (1) the power and limits of social capital, (2) political capital as a gatekeeper to development, (3) identity and attachment to place, and (4) built strengths and constraints. The study concludes that communities with well-coordinated political, social, built, and cultural capitals are more likely to “spiral up” toward sustainable growth, while those with fragmented or exclusionary networks risk “spiraling down.” By applying the CCF to rural Kansas, this study contributes to the understanding of how small towns mobilize their assets amid structural and demographic challenges. The findings offer insights for policymakers, local leaders, and development practitioners seeking to strengthen community resilience and guide equitable economic growth in rural America.Item Open Access Free choice feeding and its impact on feed efficiency and oxidative stress in growing sheep(2025) Frey, JonnThe traditional total mixed ration (TMR) is a staple in the animal feeding industry as it allows, on aggregate, for animals to perform at a high level of efficiency when feeding large numbers of animals together. However, free choice feeding could have performance benefits and help improve the well-being of animals compared to TMR feeding that is used today. With free choice feeding, animals can develop and exercise individual preference of feedstuffs which has been theorized as one potential reason for the improvement in efficiency with free choice feeding. We conducted a study using growing sheep to assess differences in performance and oxidative stress between the two feeding methods. For this study, Polypay lambs (n=23, BW = 29.7 ± 6.6 kg) were utilized with lambs being blocked by body weight and randomly assigned to either a TMR diet (CON) or a free choice diet (FCD). The diets for both TMR and the FCD were of the same primary ingredients, with the free choice group having the macro nutrients (energy and protein) being supplied by the two main components of the TMR, corn and alfalfa, offered separately in pelleted form. For determination of the oxidative health impact of the two feeding systems, blood was collected at the beginning and end of the experiment, and was analyzed for the oxidative stress metabolite malonaldehyde (MDA) and the overall antioxidant capacity (AO). The experiment lasted a total of 42 days. Lambs were fed daily with the refusals targeting 5% to allow for ad libitum consumption. Lambs were weighed weekly for the duration of the experiment and rate of gain was determined using linear regression, with the slope of the regression line being average daily gain (ADG). The heavy block of FCD had a greater (P <0.05) ADG compared to the heavy block of CON (0.23 kg/d vs 0.17 kg/d), but was similar to light blocks of the FCD and CON treatments. For DMI, TDN intake, and the variability of daily intake, there was no significant difference between treatments for any of these variables. For F:G, although no difference was observed between treatments, a significant treatment by block interaction was observed (P = 0.04). Intake of CP was a greater (P = 0.03) for CON than for FCD (0.31 kg/d vs. 0.26 kg/d). Sheep in the FCD group showed an initial preference for the alfalfa pellets, but they began to prefer corn relative to alfalfa as the experiment progressed. Measures of oxidative stress showed no differences between treatment groups at the start as well as the end of the experiment. The results of this study showed that, although some benefits to animal performance might occur with FCD, the positive impact on oxidative stress may not be true in all situations, in contrast with previously published literature.Item Embargo Development of a field water/cement ratio test using time domain reflectometry(2025) Yu, BinxiangA reliable and nondestructive method is needed to determine the water-to-cement or water-to-cementitious material ratio (w/cm) of fresh concrete for performance-based quality assurance. This study developed and validated a Time Domain Reflectometry (TDR) based method to quantify the real-time w/cm ratio of fresh concrete. Forty-eight concrete mixtures with varying w/cm ratios, air contents, and cementitious binder types (cement-only, fly ash, and slag) were tested, and TDR measurements were synchronized with conventional tests to establish a calibrated model between the apparent dielectric constant (K_a) and volumetric water content (θ_v). Data were analyzed using the statistical software R, employing group standardization, ordinary least-squares regression, and the Simulation–Extrapolation (SIMEX) method to correct for measurement-error bias. Four models developed for different cementitious binder systems showed strong consistency between measured and predicted results, confirming the reliability of the proposed calibration framework. However, as an empirical model, its applicability may be limited to the specific material range for which it was tested. Future studies should incorporate additional laboratory and field experiments, as well as explore physics-based dielectric modeling, to enhance prediction accuracy and generalization.Item Embargo Insights into the seasonal ecology and thermal biology of the lesser grain borer, Rhyzopertha dominica (Coleoptera: Bostrichidae)(2025) Christensen, DawsonOf the more than 20,000 edible plant species, maize, rice, and wheat provide half of the world’s diet. After harvest, these crops are stored for extended periods, but roughly 10 percent of global grain is lost to insect damage, costing the U.S. alone over 2.5 billion dollars annually. Among the estimated 1,500 insect species that can infest stored grain, the lesser grain borer, Rhyzopertha dominica, is a major pest capable of infesting intact kernels and causing damage directly or indirectly through contamination and promoting fungal growth. Its resilience to chemical controls and behavior of developing within grain kernels make traditional management challenging, prompting interest in alternative strategies such as cold-based interventions, including ambient and chilled aeration. Yet, the effectiveness of these methods depends on a variety of factors, including grain type, insect density, environmental conditions, and exposure duration. Here, our study addresses these knowledge gaps on how R. dominica responds to cold temperatures. A literature review first identified gaps in understanding how stored product insects tolerate cold conditions, with emphasis on R. dominica, and how this knowledge can reduce infestation risks under variable climates. Rhyzopertha dominica employs behavioral (e.g., burrowing, dispersal) and physiological (e.g., antifreeze proteins, cryoprotectants) strategies to survive harsh conditions. Commodity type and natural refugia further influence survival, and responses vary by insect species, sex, life stage, prior cold exposure, and population, highlighting the need for continued research on thermal biology to guide postharvest pest management. In line with understanding how cold treatments can be used to manage R. dominica, the first objective examined R. dominica habitats beyond stored grain, to see whether this species uses specific landscape features as alternative habitats. Field sampling in Manhattan, Kansas, indicated a strong association between beetle abundance and rodent dens. These data, combined with historical trap records, were used to develop predictive models of population trends across Kansas prairies. Incorporating climatic variables, forecasts suggest relatively stable populations through 2040, with slightly earlier seasonal emergence under warming scenarios, informing regionally adaptive monitoring and integrated pest management strategies. The second objective examined R. dominica movement under cold conditions, simulating navigation in grain bins or natural habitats. Beetles were tested across temperatures (10, 20, 30 C), acclimation (18 vs. 30 C), strains (lab colonies vs. recently collected, or wild), and sexes. Cold acclimation reduced movement at warmer temperatures but enhanced mobility in colder conditions. Females moved more than males, and lab strain beetles were more active than wild strain ones. These results indicate that acclimation, sex, and population origin strongly influence beetle movement and cold tolerance. The third objective examined how commodity type affects R. dominica survival and reproduction under warm and cold storage. Beetles were held in corn, sorghum, rice, or wheat at different temperatures (30, 18, or 5 C) for distinct exposure periods (2, 4, 8, or 12 weeks), then returned to 30 C for 6 weeks to simulate a recovery period from cold conditions. At 18 and 30 C, wheat, sorghum, and rice supported the highest adult counts, while corn was least favorable. At 5 C, counts across all grain types were relatively similar. Populations were highest at 30 C, intermediate at 18 C, and lowest at 5 °C. At 30 C, populations increased over time, stabilizing in sorghum, rice, and wheat, but continuing to rise in corn. Extended exposure at 18 C gradually reduced populations, while at 5 C, effects varied by commodity: corn and wheat remained stable at low levels, whereas rice and sorghum declined. These results indicate that even brief cold exposure (e.g., 4 weeks) can suppress reproduction, offering practical options for postharvest pest management. Overall, the work presented here emphasizes the complex interplay between thermal biology, behavioral ecology, commodity characteristics, and climate variability in shaping R. dominica population dynamics and responses to environmental stressors. Rhyzopertha dominica can withstand cold temperatures by seeking alternative habitats, acclimating gradually to cooler conditions, or persisting within the protective environment of grain. Integrating these factors into predictive models and pest management strategies will prove to be essential for optimizing cold-based interventions, enhancing sustainable grain storage, and mitigating economic losses under current and projected climate scenarios.Item Embargo Real-time monitoring of soil moisture and nutrients using an integrated dielectric sensor and an underground wireless network(2025) Han, MingqiangContinuous, accurate measurements of soil moisture and nutrients enable data-driven decisions that reduce water and fertilizer waste, improve yields, and minimize environmental impact. However, no practical sensor system currently provides these measurements simultaneously with the required accuracy. Dielectric spectra sensors offer a promising solution, but significant challenges, including system reliability, field validation, and identifying frequency responses specific to individual soil properties, remain. This dissertation addresses these challenges by developing and validating an integrated system for accurate measurement of volumetric water content (VWC), nitrate-nitrogen (NO3-N), and ammonium-nitrogen (NH4-N), with data transmitted through wireless underground networks, to advance sustainable agricultural management. A multi-layer soil propagation model was introduced to predict signal attenuation in complex soil profiles. Extensive field tests across different soil types were conducted to validate this model and demonstrate the feasibility of wireless underground communication using various transceivers. The proposed model significantly improved attenuation estimation, and field results confirmed reliable underground data transmission at depths of up to 50 cm. LoRa-based technology was selected as the preferred wireless communication method due to its robust performance across soil conditions. A dielectric sensor system capable of measuring both magnitude and phase responses from near DC to 1 GHz was designed and implemented. These measurements provide information on soil permittivity, which can be used to estimate key soil properties. The system integrates circuits for signal generation, conditioning, processing, data acquisition, storage, and wireless transmission, all controlled by an STM32F407 microcontroller with efficient power management. System performance was thoroughly tested and validated. An integrated software platform with a user-friendly graphical interface was developed for real-time data visualization and interpretation. Robust communication protocols were established for seamless connectivity among wireless sensor nodes and user devices. The interface supports data collection setup, real-time monitoring, sensor geolocation, and integration with weather data. Laboratory and field experiments were performed to evaluate sensor performance for soil property measurement. Multiple experimental datasets were analyzed to identify the most responsive frequencies for detections of VWC, NO3-N, and NH4-N using variable selection methods, including competitive adaptive reweighted sampling (CARS), minimum redundancy maximum relevance (MRMR), and successive projections algorithm (SPA), in conjunction with artificial neural network (ANN) models. The system achieved good predictive performance, with selected frequencies enabling the development of final models yielding test set R2 values of 0.80, 0.66, and 0.76 for VWC, NO3-N, and NH4-N, respectively. In summary, this dissertation introduces a comprehensive soil monitoring system that delivers accurate, real-time data to advance sustainable agricultural practices.Item Open Access What’s the buzz?: a dual-scale assessment of Kansas bumble bee species to inform future conservation efforts(2025) Holthaus, DanielleThe decline of bumble bee (genus Bombus) populations across North America, attributed to factors such as habitat loss/ fragmentation, increasing use of pesticides, and climate change, poses significant concerns for both natural ecosystems and agricultural productivity. Two bumble bee species found in the Great Plains are imperiled, which necessitates further research exploring where they are located, how their habitats differ from species that are stable, and what land management techniques can be implemented to benefit the bumble bee community as a whole. In this thesis, I used experimental and modeling methodologies to assess how Kansas bumble bee species are affected by environmental factors on two different scales. On a local scale (Chapter 1), I take an experimental approach by conducting a two-year field study to investigate the direct and indirect effects of bison (Bison bison) grazing and fire frequency (common grassland management strategies) on bumble bee abundance, community composition, and plant interactions. I found that the presence of bison indirectly increases total bumble bee abundance by means of increasing floral resource availability; there were interactive effects with fire frequency. Community composition did not differ significantly between grazing treatments; however, there were differences in host-plant interactions among bumble bee species. On a state-wide scale (Chapter 2), I use species distribution models to understand differences in habitat selection and spatial distributions between common and threatened species in Kansas. While most findings were species-specific and not characteristic of “common” or “threatened” groups as a whole, one species of least-concern deviated the most in terms of habitat associations. In general, all species were negatively associated with monoculture crop coverage. Climate factors appeared to be less important drivers of distribution than landscape factors. Model-predicted maps created from each species’ most significant set of predictor variables display hotspots where individuals are most likely to be detected across Kansas. Such maps are crucial for designating priority areas for threatened species protection. Overall, this research provides valuable insights into the ways in which grassland management, land cover, and climate factors affect bumble bee species for the purposes of assisting with targeted conservation efforts across Kansas and the entire Great Plains.Item Embargo Understanding Listeria biofilms: formation, ecology, and control in the produce industry(2025) Deniz, AysuListeria monocytogenes, a major foodborne pathogen, has been a growing concern in the fresh produce industry and is increasingly recognized as a vehicle for transmission of foodborne illnesses. Its persistence and contamination potential are strongly associated with its ability to form biofilms. Hard-to-clean sites in food processing environments can provide favorable conditions for biofilm establishment and survival. Exposure of these biofilms to sublethal concentrations of sanitizers can trigger stress response mechanisms, leading to alterations in gene expression that promote adaptive response. Beyond single-species systems, a further challenge is the frequent occurrence of L. monocytogenes in multispecies biofilms, particularly with Pseudomonas spp., a common spoilage microorganism. These mixed communities exhibit enhanced resistance and tolerance to sanitizing practices, creating greater challenges for effective control. Therefore, the main objectives of this study were to: 1) Assess the growth of L. monocytogenes biofilms on common food processing surfaces used in the fresh produce industry and evaluate the efficacy of commercially available sanitizers alone or simultaneously with UV-C light; 2) Characterize the transcriptional response of L. monocytogenes biofilms exposed to sublethal concentrations of commercial sanitizers and identify mechanisms involved in biofilm adaptation; and 3) Investigate the interactions between Pseudomonas fluorescens and L. monocytogenes in dual-species biofilms and evaluate the efficacy of commercially available sanitizers against these biofilms across different food-contact surfaces. Multi-strain L. monocytogenes biofilms were grown in a Centers for Disease Control and Prevention (CDC) biofilm reactor on stainless steel, nylon, polyvinyl chloride (PVC), high density polyethylene (HDPE), and Teflon for up to 96 h. Mature biofilms were exposed to 120 ppm peracetic acid (PAA), silver dihydrogen citrate (SDC; 4.85% citric acid and 0.003% silver ions), 4% lactic acid, and UV-C light (254 nm) for 1 or 5 min by spraying. Biofilm architecture was evaluated using Laser Scanning Confocal Microscopy (LSCM) before and after treatments. Uninoculated surface materials showed different topographical characteristics and when mature biofilms were treated for 1 min with different sanitizers, biomass was visibly affected. Antimicrobial treatment and the interaction of treatment and material showed significant effects (P < 0.05). All tested liquid sanitizers significantly reduced biofilm cell populations as compared to controls (P < 0.05), with PAA and lactic acid demonstrating the highest efficacy across surfaces. However, simultaneous application of UV-C light with sanitizers did not statistically improve treatment efficacy. Given the observed variation in sanitizer efficacy against L. monocytogenes biofilms populations observed, transcriptomic analysis was conducted to further explore the relationship between sanitizer-induced stress and gene expression. Biofilms were exposed to sublethal concentrations of PAA (10 ppm), chlorine (10 ppm), SDC (4.85% citric acid and 0.003% silver ions), and lactic acid (0.4%), with untreated biofilms serving as controls. L. monocytogenes biofilms responded differently to sublethal stresses of these sanitizers. Among them, chlorine and peracetic acid induced the most rapid and significant transcriptional changes. Comparative analysis of differentially expressed genes (DEGs) revealed both unique and shared transcriptional responses across treatments. Chlorine induced the highest number of unique upregulated genes, while chlorine and PAA shared a subset of commonly regulated genes. This suggested both distinct and overlapping stress response mechanisms depending on the sanitizer used. Chlorine exposure triggered regulatory and transport systems, while PAA induced ion transport and ABC transporters. These sanitizer-specific responses suggested distinct adaptive strategies that may contribute to persistence. Since complex interspecies interactions can enhance resistance and tolerance to sanitation efforts, this study also evaluated the efficacy of commercial sanitizers against dual-species biofilms of L. monocytogenes and P. fluorescens. Biofilm production capacities of these species were first assessed by crystal violet staining. Dual-species biofilms were then grown in a CDC biofilm reactor on stainless steel, PVC, Teflon, and HDPE surfaces at 22 2C for 96 h. Mature biofilms were treated by immersion with the previously tested sanitizers, along with chlorine (500 ppm) for 5 min. Surviving cells were recovered on selective and general media. In addition, growth dynamics of both species were monitored over time, and LSCM was used to visualize colonization patterns and spatial organization within the biofilms. Results revealed that both P. fluorescens and L. monocytogenes were found to be biofilm formers with different production capacities and P. fluorescens showed significantly higher biomass production than L. monocytogenes (P < 0.05). Material, treatment, and their interaction had significant effects on microbial recovery (P < 0.05). Among sanitizers tested, chlorine was the most effective showing enhanced effectiveness on stainless steel where the total counts were reduced from 8.43 ± 0.32 log CFU/coupon to 5.26 ± 0.09 log CFU/coupon. A similar trend was observed when L. monocytogenes and P. fluorescens populations were enumerated individually. PAA was also effective against dual-species biofilms. On HDPE, PAA treatment resulted in the combined counts of 6.27 ± 0.15 log CFU/coupon where untreated control was 8.63 ± 0.34 log CFU/coupon. Overall, this study demonstrates that L. monocytogenes biofilms exhibit sanitizer and surface dependent responses and provides insight into how interspecies interactions and sanitizer adaptations affect their persistence on food processing surfaces. These findings provide insightful information on the use of a combined sanitizing approaches and support the development of more effective strategies for controlling biofilms on food processing surfaces in the fresh produce industry.Item Embargo Machine learning integration of UAS-based thermal and multispectral imaging for precision irrigation in corn(2025) Abon, John Eric; Sharda, Ajay; Sharda, Vaishali; Aguilar, Jonathan; Ciampitti, IgnacioWater scarcity and climate variability are intensifying the challenge of sustaining corn (Zea mays L.) yield while minimizing irrigation inputs. The study employed Unmanned Aerial System (UAS)-based thermal and multispectral remote sensing with advanced machine and deep learning methods to create a comprehensive, field-scale framework for precision irrigation and crop productivity forecasting. UAS-based thermal imaging was deployed to quantify the spatial variability of crop water stress under three irrigation treatments—33% (P33), 67% (P67), and 100% (P100) of full crop water requirement across six reproductive stages (R1—R6). High resolution canopy temperature maps were converted to the Crop Water Stress Index (CWSI), a standardized indicator of water stress revealing severe stress in the P33 treatment (CWSI > 0.80, canopy temperature > 45°C), moderate stress in the P67 treatment (CWSI 0.40-0.75), and optimal conditions in the P100 treatment (CWSI < 0.40). Temporal analysis confirmed peak stress during early reproductive stages, and non-parametric statistics (Friedman χ² = 6.33, p = 0.042) verified significant treatment effects, indicating the value of UAS-derived thermal data for site-specific irrigation scheduling. Temporal-Spatial Fusion Network (TSFN) was developed to predict corn yield by integrating thermal and multispectral imagery collected by unmanned aerial systems (UAS) across six maize reproductive stages (R1 to R6) with deep learning modules: convolutional neural networks (CNNs) to learn intra-plot spatial features, Graph Neural Networks (GNNs) to model inter-plot spatial dependencies, and gated Recurrent Units (GRUs) with attention mechanisms to capture sequential temporal dynamics. High resolution imagery was acquired weekly and used to derive vegetation indices (NDVI, NDRE, GCI, MTCI, EVI) and crop water stress Index (CWSI), enabling spatially explicit tracking of crop health and water stress responses. TSFN combines the model significantly outperformed traditional machine learning methods and standalone deep learning models. It achieved an R² of 0.79 and RMSE of 13.10 bu/acre, surpassing CNN-GNN and ensemble baselines. Later reproductive stages (R4-R6) contributed most to predictive accuracy, while early-stage data (R1-R3) supported timely in-season diagnostics. The model performed best under moderate and deficit irrigation (P67 and P33) due to increased spectral variability caused by crop stress. Unmanned aerial system (UAS) multispectral imagery was combined with machine-learning and deep learning models to generate high-resolution evapotranspiration (ET) estimates. NDVI-derived crop coefficient (Kc) and on-site ET-gage reference evapotranspiration (ETo) informed model training. Random Forest delivered near perfect accuracy across irrigation levels (R² = 1.00 at R1 to R3, RMSE = 0.00 mm day -1) and only small reduction at R4 (R² = 0.97). ResNet18 consistently outperformed the CNN and achieved strong agreement with field measurements (R² ≈ 0.95–1.00, RMSE ≈ 0.00-0.17 mm day -1). Stage-wise evaluation revealed ResNet18 remained highly accurate during most reproductive phase, but showed moderate dip at R4 (R² = 0.95). Ablation analysis confirmed that late season imagery was essential for model performance. Removing R5, which contains the highest ETc values (≈ 6-8 mm day-1), produced largest decline in predictive accuracy, reducing R² to 0.93 and raising RMSE to 0.28 mm day-1), whereas omitting R4 had minimal impact and in some cases slightly improved accuracy. These studies effectively delivered information that integrating UAS thermal and multispectral sensing with advanced analytics enables zone-level mapping of crop water stress, accurate yield prediction, and operational ET estimation. The resulting framework provides actionable, data-driven irrigation strategies that reduce water use while sustaining corn productivity under variable irrigation regimes.Item Embargo Development of novel, chemically-modified hempseed protein adhesives for wood bonding applications(2025) Barretto, RoselleThe dominance of petroleum-derived and formaldehyde-based wood adhesives poses serious environmental and health challenges, emphasizing the urgent need for sustainable, fully bio-based alternatives. This dissertation investigates the development of hempseed protein adhesives through a comprehensive approach involving extraction, structural characterization, and systematic chemical modification aimed at improving bonding performance, thermal stability, and water resistance. Hempseed protein, rich in edestin (11S) and albumin (7S) fractions, represents a renewable and abundant biopolymer with intrinsic adhesive potential. In the first study, hempseed protein isolates (HPI) were successfully extracted from commercial and Hlesia hempseed meals using alkaline solubilization and isoelectric precipitation. Structural analyses identified major protein subunits with molecular weights of 18–20 and 34 kDa, corresponding to edestin and albumin fractions. The native HPIs showed promising adhesive properties attributed to their intrinsic high hydrophobic amino acid content, which confers low water solubility and contributes to inherent wet bonding strength. Crosslinking with glutaraldehyde at optimal concentrations (20–80 μM) significantly enhanced adhesive performance, with dry shear strengths up to 5.74 MPa and wet strengths up to 2.86 MPa at press temperatures of 190 °C. Notably, crosslinked HPIs maintained substantial wet adhesion at lower press temperatures (150–170 °C), broadening processing windows. Morphological characterization via SEM revealed smoother, more compact fracture surfaces in modified adhesives, indicative of improved cohesive bonding and interfacial adhesion. The second study evaluated bio-based modifications employing glyoxal and zinc chloride (ZnCl₂) as crosslinkers. Glyoxal modification markedly increased adhesive strength across all conditions, achieving dry, wet, and soaked shear strengths of up to 5.69, 2.68, and 4.91 MPa, respectively. ZnCl₂ induced moderate but consistent improvements, with corresponding strengths of 4.20, 2.10, and 3.89 MPa. Combining glyoxal and ZnCl₂ yielded intermediate performance, suggesting limited synergistic interaction. Thermal analysis demonstrated substantial enhancement of thermal stability upon glyoxal treatment, with denaturation temperatures elevated to approximately 146–148 °C and corresponding increase in enthalpy, indicating strengthened protein network structures. SEM images corroborated densification of the adhesive matrix with glyoxal, contrasted with less compact morphology for ZnCl₂ modifications. Surface hydrophobicity increased significantly with glyoxal, supporting improved moisture barrier properties essential for wet-performance. Rheological assessments revealed stable shear-thinning behavior suitable for processing, with pot-life viscosity stability maintained for up to 24 hours at 25 °C and under refrigerated conditions, ensuring feasibility for industrial application. The third study focused on fully bio-based adhesive formulations through synergistic crosslinking of HPIs with glucose and citric acid, leveraging Maillard-type and esterification chemistry. Citric acid modification alone enhanced crosslink density, raising a dry shear strength to 3.07 MPa and thermal stability above 144 °C denaturation temperature. Glucose contributed to formation of Schiff bases and Maillard reaction products, leading to further gains in dry strength (maximum 3.46 MPa) and wet strength (1.61 MPa) as well as increasing surface hydrophobicity over to 78 μg/mg protein. When combined, glucose and citric acid yielded strong synergistic effects, with adhesive strengths reaching 4.76 MPa (dry), 2.49 MPa (wet), and 4.14 MPa (soaked), alongside durable water resistance demonstrated by retention of 82.9% mass after soaking. DSC analysis indicated cooperative stabilization reflected in increased denaturation and endset temperatures exceeding 160 °C and elevated enthalpy values. FTIR and XRD analyses confirmed formation of ester bonds and dense amorphous networks concomitant with reduction of salt crystallinity. SEM revealed continuous, crack-free fracture textures consistent with robust interfacial bonding and cohesive strength. Rheological properties showed balanced viscoelastic behavior, ensuring processability and application stability. Collectively, these studies establish the mechanistic basis and processing strategies for converting hempseed proteins into high-performance, formaldehyde-free wood adhesives. The results not only demonstrate the feasibility of hempseed protein as a competitive biopolymer but also advance the broader adoption of sustainable adhesive technologies within the bioeconomy.Item Open Access Bacteriophage based diagnostics for on-farm bovine mastitis testing(2025) Bates, KristinBovine mastitis remains one of the most costly and persistent diseases in the global dairy industry, causing annual losses of up to 32 billion USD through reduced milk yield, treatment costs, and premature culling. Current diagnostic tools – such as somatic cell counts, microbial culture, and PCR – are hindered by slow turnaround times, high costs, and technical demands, leading many producers to default to broad antibiotic use. This practice fuels antimicrobial resistance and limits targeted disease control. Bacteriophage-based diagnostics offer a promising alternative. Phages, viruses that specifically infect bacteria, provide highly selective detection of mastitis-causing pathogens such as Staphylococcus aureus, Streptococcus uberis, and Escherichia coli. Reporter phages genetically engineered to express measurable signals upon infection can deliver rapid, pathogen-specific results within minutes. Lyophilization enhances reagent stability, while colorimetric reporter systems enable simple, visual interpretation suitable for on-farm use. Beyond mastitis, phage technologies are already established and applied in food processing as antimicrobial washes to reduce Listeria monocytogenes, Salmonella spp., and E. coli O157:H7 contamination. Extending this proven safety record to diagnostic applications could improve surveillance throughout the dairy supply chain. By combining precision, speed, and field applicability, bacteriophage diagnostics represent a practical and sustainable advancement in veterinary and food safety microbiology. Continued development of multiplex assays, field validation, and regulatory frameworks will be critical for translating this technology into routine farm and processing practices.Item Open Access Missouri ELL policies and mainstream teachers' preparedness perceptions: A three-article dissertation(2025) Kearbey, JohnThis dissertation examined mainstream teachers' perceptions of preparedness to teach English Language Learners (ELLs) in Missouri's public schools through a three-article format, consisting of a systematic literature review, policy analysis, and quantitative evaluation. Grounded in Vygotsky’s Sociocultural Theory, Krashen’s Input Hypothesis, and Siemens’ Connectivism, the study addressed gaps between policy mandates and classroom realities amid increasing linguistic diversity. The first article reviewed 14 studies from 2003–2024, and revealed persistent under-preparation among mainstream teachers, influenced by inadequate pre-service training, variable professional development (PD), teacher beliefs, and institutional support. The second article traced Missouri's ELL policies from the Bilingual Education Act (1968) to the Every Student Succeeds Act (2015), and highlighted advancements like the ELL endorsement (5 CSR 20-400.570) and noted implementation inconsistencies, funding disparities, and rural-urban divides. The third article analyzed Missouri's First-Year Educator Survey data (2016–2024) using multiple linear regression and found that teachers rated their ELL preparedness lower than for other areas (R² = .1599 for teacher predictors), with principal evaluations showing limited alignment (R² = .0054). Findings underscored systemic gaps: teachers lacked SLA training, policies failed to ensure equitable resources, and rural districts struggled more than other districts. Implications included embedding ELL pedagogy in teacher preparation, mandating sustained PD, and reforming policies for better accountability. This work ultimately calls for equity-focused reforms to enhance ELL outcomes and sought to inform broader educational practice.Item Open Access The Role of Digital Media in Motivating Teenage Pregnancy Prevention Among Teenagers in Ghana(2025) Abdul Malik, KaramatuThis thesis investigates the role of digital media in shaping knowledge, information-seeking behaviors, and preventive health actions related to teenage pregnancy among adolescents in Ghana. With the growing reliance on digital platforms for sexual and reproductive health information, this study examines how digital media influence adolescent engagement with pregnancy prevention in a context where cultural stigma and limited access to services persist. Grounded in Protection Motivation Theory (PMT) (Rogers, 1983), the research evaluates the effects of perceived severity, vulnerability, response efficacy, self-efficacy, and response costs on pregnancy-related knowledge, digital media engagement, online health information-seeking, and preventive behaviors. Additional variables include demographic characteristics and media-related factors that shape adolescent reproductive health decisions. A quantitative cross-sectional survey was conducted with adolescents aged 18–19 (n = 429). Descriptive statistics, including means, standard deviations, and Cronbach’s α, were computed to assess reliability of the constructs. Correlation and hierarchical regression analyses were performed to test the hypotheses and answer the research questions. Findings indicate that self-efficacy (β = .337, t = 4.01, p < .001) and response costs (β = .235, t = 3.26, p < .01) significantly predicted digital media engagement, while perceived severity (β = –.303, t = –3.48, p < .01) was negatively associated. Protective behaviors were significantly predicted by response efficacy (β = .324, t = 5.30, p < .001), self-efficacy (β = .166, t = 2.62, p < .05), online information-seeking (β = .305, t = 5.45, p < .001), and digital media use (β = .087, t = 2.63, p < .05). Correlation analyses further confirmed strong positive relationships between online health information-seeking, response efficacy (r = .769, p < .001), and self-efficacy (r = .792, p < .001). Regression models explained significant variance across outcomes, demonstrating that efficacy beliefs and digital engagement, rather than threat perceptions, are key drivers of preventive behavior. These findings underscore the explanatory power of PMT while extending it into a digital health context. This study highlights the potential of digital media to serve as an effective platform for motivating adolescent pregnancy prevention in Ghana. It emphasizes the importance of designing culturally relevant, accessible, and empowering digital interventions that build self-efficacy, enhance trust in digital health tools, and address barriers that limit sustained engagement.Item Open Access Strategies for evaluating ectoparasiticides in companion animals(2025) Sutherland, CameronEctoparasites including fleas, flies, lice, mites, and ticks are targets of past, present, and future veterinary concern. Controlling ectoparasites is critical to mitigate irritation, potential allergies, and transmission of vector-borne diseases. This dissertation focuses on the process evaluating ectoparasiticides before and during market release with an emphasis on the isoxazoline drug class. Chapter 2 focuses on an in vitro strategy for ectoparasite rearing and potential use for parasiticide testing. The proposed model utilizes materials that are accessible for small-scale research groups such as universities, industries, and contract research organizations. This model is a 3D-printed artificial flea feeding system that showed success rearing multiple generations of Ctenocephalides felis fleas. The ability to rear fleas using this model would make in vitro ectoparasiticide testing more accessible to researchers regardless of budget or scale. Chapter 3 focuses on the evaluation of fluralaner oral and topical canine formulations in an off-label use-case by administering it to horses, an animal with no published pharmacokinetic data from the isoxazoline drug class. Ectoparasite control in horses is of great veterinary interest as they can be responsible for pruritus, discomfort, and/or vector-borne disease transmission. This study demonstrated that fluralaner reached a higher plasma concentration when administered orally but had a longer half-life when administered topically. This provides a starting point for finding an appropriate dose and route for developing a highly effective, long-lasting ectoparasite product for horses. Chapter 4 focuses on a post-approval marketing field study administering an oral formulation of lotilaner to animals in homes experiencing flea infestations. This study showed the ability to eliminate environmental flea infestations by focusing treatment efforts on the animals living within the house rather than broad, premises sprays. The contents of this dissertation endeavor to elucidate novel strategies for ectoparasiticide testing while also highlighting the importance of data generated from field studies.Item Open Access Meaning-making in the academic advising relationship: Reflections on student success(2025) Cole, HelenaThis phenomenological study sought to explore how first-year exploratory majors made meaning of their academic advising experiences. Using the literature surrounding meaning-making framed within the relational component of NACADA: The Global Community for Academic Advising’s core competency model, it interrogated the role that academic advising, and in particular the advisor/advisee relationship plays in a student’s “successful” college experience. Significant to this inquiry was the challenge in defining “student success;” what may contribute to this challenge is the presence of two different, but at times overlapping constructs—that of student success and institutional success—creating a conundrum for any further exploration of what constitutes that “successful” experience. This qualitative study used semi-structured interviews and a reflective questionnaire, as well as a brief online document analysis, to explore the lived experiences of first-year students who were advised by primary-role advisors as exploratory major students in the first and second quarters of attending a four-year public university. Initial exploration and analysis of the data from the interviews did not reveal significant meaning-making experiences on the part of the participants (the focus being more on sense-making); however, answers to the reflective questionnaire indicated that the first interview may have caused participants to think more deeply about their advising experiences and the relationship they had with their advisors. Reflections on the findings of this study, as well as the research process itself—the story of the story—reveal more questions than answers. This further challenges the academic advising community, and perhaps higher education in general, to continue to explore and yes, even make-meaning of, their approaches to the student success conundrum.Item Embargo A comparative study of plain and reinforced concrete isolated footings: structural behavior, constructability, and embodied carbon(2025) Arnold, ByronA major challenge confronting architecture, engineering, and construction (AEC) industry is the threat of climate change – an issue to which the industry itself is a significant contributor. As a result, AEC professionals carry a responsibility to improve material efficiency and reduce embodied carbon across common structural systems. One opportunity lies in re-evaluating isolated spread footings, a ubiquitous foundation element in low-rise buildings throughout the United States of America. These footings, typically composed of concrete and reinforcing steel, transfer gravity loads through concrete compression and soil bearing while also resisting incidental shear and moment demands. Although concrete alone can resist axial, shear, and flexural forces to a limited degree, standard practice relies on reinforcing steel to provide adequate shear and flexural capacity. This report examines the ACI 318-19(22) code provisions on plain concrete, reviews design requirements for reinforced foundations, and compares the capacities of plain versus reinforced spread footings subjected to concentrated axial loads of 50, 100, 200, and 300 kip concentric axial loads. Key site and material parameters such as allowable soil bearing capacity (2,000 psf, 3,000 psf, and 4,000 psf) and concrete compressive strength (3,000 psi and 4,000 psi) are varied to enable direct comparisons. To evaluate environmental implications, the increased concrete volume required for plain concrete design is assessed relative to the reduced use of reinforcing steel. It was found that when the ultimate axial load is 50 kips or smaller, plain concrete footings have a reduced environmental impact conversely when the ultimate axial load is 100 kips and greater, reinforced concrete footings have a greater material efficiency that yield a lower embodied carbon. Finally, the report discusses broader constructability and sustainability considerations, including procurement, transportation, and installation impacts associated with each footing type.Item Open Access Integrating communication and collaboration: A study of Kansas water scientists and interdisciplinary teams(2025) Donaldson, RebeccaWater scarcity is a growing global concern, and in Kansas, issues such as limited precipitation and increasing pressure on both surface and groundwater resources have made water research and management a critical priority. Because agriculture accounts for most water use in the state, effective communication from scientists is crucial for supporting informed decision-making among issue holders. The following studies explored how Kansas water science experts communicate their findings and efforts to public audiences, as well as how an interdisciplinary water research team engages in collaborative, transdisciplinary work. This thesis consisted of two qualitative studies. In Study 1, semi-structured interviews were conducted with 21 water science experts across Kansas to identify communication practices, challenges, and perceptions. Findings from this phase informed Study 2, a case study exploring how members of the Kansas Water Institute (KWI) collaborate, exchange knowledge, and engage with issue holders. The case study included nine individual interviews and a focus group that incorporated a visual network mapping activity to better understand team and issue holder relationships. Results indicated that while many water science experts lack formal communication training, they actively adapt and “figure out how to get it done” through experience and collaboration. Their audiences span a diverse range of groups, including producers, policymakers, and the public. The water industry itself is inherently interdisciplinary, and the KWI team was intentionally assembled by the institute’s leadership based on complementary skills and team dynamics. Participants identified barriers to communication and collaboration at internal, external, and structural levels, but also emphasized the importance of leadership and interpersonal relationships in supporting networking and team success. Findings suggest that the water science industry could benefit from increased emphasis on science communication training to strengthen outreach and public engagement. Future interdisciplinary research teams should prioritize intentional formation and collaboration strategies. Additionally, future research could expand on visual methods for mapping social networks and examine how experts’ perceptions of water issues influence their communication priorities and strategies.
